The present invention relates to subterranean treatment fluids and, more particularly, in some embodiments, to methods of designing treatment fluids based on solid-fluid interactions.
A wide variety of fluids may be used in subterranean operations, including, but not limited to, drilling fluids, cement compositions, completion fluids, and fracturing fluids. The fluids may be introduced into a well bore in accordance with known techniques. It may be desirable to know various characteristics of the fluids to determine how the fluids will act upon being introduced into the well bore.
Some fluids used in subterranean operations may carry particulate, and it is typically desired for the fluids to support the particulate in suspension for at least some period of time. In other words, the particulate should, for example, be dispersed throughout the fluid during at least part of the time the fluid is used in the well bore. For example, a fracturing fluid may include a gelled base fluid and a quantity of a particulate (e.g., proppant). One example of a suitable proppant is sand. The gelled base fluid generally supports the proppant such that the proppant is suspended in the fluid during the time the fracturing fluid is introduced into the well bore. The fracturing fluid may be introduced into the formation at a hydraulic pressure sufficient to create or enhance at least one or more fractures in the formation. Enhancing a fracture includes enlarging a natural or preexisting fracture in the formation. Thereafter, the fluid may be recovered from the well bore with the proppant remaining in the fracture. The proppant are thought to prevent the fractures from fully closing upon the release of hydraulic pressure, forming conductive channels through which fluids may flow to a well bore to ultimately be produced.
In general, fracturing fluids may be designed to have sufficient viscosity to generate fracture geometry and transport proppant. Accordingly, fracturing fluids may be subjected to extensive testing on high-temperature rheometers to ensure that they have sufficient viscosity for performing the intended purpose and break within a suitable timeframe for the application. Slurry viscometers may also be used, for example, to indicate time periods during which the fracturing fluid is supporting proppant in suspension and when the proppant has settled. In fluid design, it has generally been assumed that proppant has a negligible effect on fluid properties and that all proppants of a given mesh size and density will be transported equally.